Originally published at: Poll: FAA Unleaded Avgas Transition Plan
What are your thoughts on the FAA’s newly released avgas transition plan draft?
I think the whole thing is Daft. It doesn’t pass the common sense smell test that with so little 100 LL Avfuel being burnt per year compared to the billions of gallons of leaded fuel burnt for nearly a century that this minuscule amount will amount to any health improvement or deterioration. Of course in the fairy land of utopia it would work very well.
With all that said, I believe in checking all the boxes except the last two. I am of the firm opinion of loose nuts in the power of authority causing catastrophic events.
As PS has anyone noticed that Global warming/Climate change has taken a back seat to AI electricity generation thru whatever means possible to include Coal, Nuclear, and fossil fuels?
It’s complex and extensive but lacks a specific timeline due to a multitude of variables. The sections on airport grants to incentivize early adopters is hard to understand and requires detailed knowledge of the grant processes which most readers don’t have. I don’t think we’ll make 2030, which is only 4 years away. Fuel testing alone will probably take that long. By then we’ll have another administration in place with different priorities. There needs to be federal legislation that establishes cutoff dates for testing to incentive the different parties involved. Financial incentives should be tied to meeting testing milestones. If they miss them, too bad - no money. The same for fuel distribution and availability at FBOs.
Of course if this transition is going to be based on the ETBE containing fuel (LB) then this is never ever going to be a global ‘drop in replacement fuel’, and the plan is relatively pointless because the manufacture and/or importation of fuels containing ETBE is prohibited into the country with the world’s second largest fleet of GA aircraft due to Australia’s laws. Our country is hugely reliant on the Great Artesian Basin (GROUND WATER). I’ve been heavily across issues related to ETBE/ MTBE and the Australian situation for many years. Here’s your ‘quick search results’ … " the supply of petrol containing ETBE (ethyl tertiary butyl ether) as an additive is prohibited in Australia.
Australian regulations, such as the Environment Protection (Motor Vehicle Fuel Quality) Policy 2002 in South Australia and national fuel quality standards, ban or severely limit the use of ethers like ETBE, MTBE (methyl tertiary butyl ether), and TAME (tertiary amyl methyl ether) due to environmental concerns, specifically the risk of groundwater contamination from leaking storage tanks.
- Prohibition Details: Fuel suppliers are legally mandated not to add ETBE, MTBE, or TAME during the production process of petrol intended for supply.
- Environmental Reasons: These substances are highly mobile and persistent in water, posing significant risks to water sources if released from storage systems. **"
So sorry guys, you’ve got a BLOODY LONG WAY TO GO before you’re even close to approving a global ‘drop-in replacement’. Should have done your homework first, before wasting tens of millions of dollars.
Regardless of whether you believe there is an environmental problem with leaded avgas, the single Western company that makes the TEL used in avgas is not going to make it forever. Because the market for TEL is so small and the health/environmental risks are so great, no one is going to step in to fill that tiny market niche. Like it or not, 100LL is going the way of the dodo, and thus alternative fuel for the GA fleet is required.
GA piston air-cooled engines have never been known to be all that durable or dependable for a multitude of reasons. Many are operating fine with autogas. I’ve seen no data that it has caused any new operating issues or at the other end, fatalities. It seems the lower end GA aircraft owners are paying the price for a very small group of owners. I would suggest the FAA allow engines under 300 HP to run on non-oxygenated autogas. Let the operators decide.
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When I started flying, 100LL was the “new thing.” 80 (with a maximum, but no minimum Pb content), 100/130 with lots a lead, and the jet fuels. Most airports had 100 or 100LL and 80. My airplane (same one 35 years later) loved the strawberry soda pop Avgas 80/87 until it disappeared in the early 1990s. I switched to 100LL and within 100 hours was replacing cleaning or otherwise deleading these plugs in my well cowled O470R with coolish CHTs. I got the Petersen STC shortly before the EAA STC came out. It allowed me to burn leaded, unleaded 80/87 mogas which was mostly ethanol free then. When 80/87 Avgas went away, many airports I frequented throughout the US sold Mogas and a few still do. I buy it. I’ve also used the Swift Fuels as my 80 octane engine permits it when it came available at my fuel stop in central Wisconsin. I even had to buy a tank of 100/130 Green coming back from northern Canada as that was all that was available at that stop. The airplane survived and ran over 1200 hours past its recommended TBO.
Here are the problems with the FAA’s one size fits all approach. First, there has never been a single piston engine fuel compatible with everything. ’
Single grades were tolerated, sometimes poorly as in my airplane, but tolerated and reasonably safe with extra maintenance.
Second, most airports had dual fuel capacities until the crazy idea that 100LL was a “universal” replacement fuel. Since 80 requires no TEL and the Pb spec is mainly to limit Pb not mandate it and I am told that the main reason it had that spec was to permit single pipeline and tankage washout for all avgas instead of requiring separate infrastructure for each.
So, if that is the history, then how on earth does the FAA, or anyone else think we can make a single grade fuel for every airplane made? We can’t even do it for cars with sophisticated instrumentation and control, else why would every gas station I’ve been to in the US and Canada carry 87, 88, 91, 94 octane fuels in larger areas. Most airports still have double tanks, one for one fuel and another for a different grade. Comixing of the various fuels usable was always allowed (80, 100, 100LL, mogas). There was no mandate to burn a specific brand of fuel, any fuel that met the specs was allowed, except I couldn’t use mogas for Part 135 ops.
And the 100LL one shoe fits all approach had a negative impact on the transition to a lead free fuel. Suddenly airplanes that traditionally had low compression engines found themselves outfitted with high compression engines requiring leaded fuel. Even a C152 as Lycoming bumped up the compression to use 100LL. Counterproductive to the current goal.
@N6589M has it exactly right. If we are restricted by the present stupidity to a single brand of fuel per STC/engine/airframe, then airports will have to carry every single brand, let alone every single operational grade of fuel, which is exactly the course that at least one of the fuel manufacturers is advocating.
Sheer follly, incredibly wasteful of distribution channels and operationally unsound. I check all the boxes except the last two as well. Although I would prefer the convenience of a fuel pump on field, I now carry a transfer tank, and have aux tanks to bring my fuel with me giving me a 1000 nm range on local mogas because I don’t need 100LL and it causes substantial operational issues. And electronic ignition didn’t hurt.
Art, and Skygypsy have some valid input here. I would like to add that the comment function is not the typical NPRM type of setup, but drops you into the draft document area for an email address. Like Art, I had excellent results from 1986 on, using MOGAS. In recent years, it seems to be a bit aggressive on 60 year old Piper gas tank sealant! I made the following comments via email to Mr. Paul Wrzensinski:
"I have read the draft and have 2 concerns that I feel should be addressed.
EXHAUST EMISSION ASSESSMENTS is listed in a header in the document, but is never specifically addressed.
In the definitions, MOGAS is not listed, nor is automobile fuel.
Specifically ASTM spec D439, and D4814 are not mentioned. STC cancellation, however, is mentioned. Will Autogas STCs be cancelled?
I believe that it would be remiss to fail to address interoperability with MOGAS in this document, considering the number of STCs in the field.
Also Rotax engines are approved for MOGAS. The Tecnam P2006T TCDS A62CE for example is approved for MOGAS ASTM D4814 (Min RON 95) & AVGAS 100LL (ASTM D910)."
For avweb readers, here is a link regarding emissions changes with various oxygenates: AMF
The draft document does mention anti-detonant injection, which is crazy considering that in modern times this method specifically was used to allow MOGAS use in big bore Continental engines.
I’ve asked the question, many times, "How much actual lead pollution do we get from 100LL? I have never had an answer that included any scientific data. Maybe I’m not asking the right people? To me, and I’m an environmental kind of person, you have to look at the whole scene. I am already not certain that high powered piston engines will run on the unleaded fuels. I haven’t seen any data to support that fact. However, once again, I’'m possibly not looking in the right areas. There are a lot of tube powered high altitude piston aircraft flying, but if you lump all the pistons powered aviation engines into one, how much do they contribute to lead health issues? I don’t know. Personally I don’t trust any groups, pro or con various issues. Simply because they only quote data that supports their cases.
I certainly can make a case for using unleaded auto fuel. Millions of cars and trucks on the road in the country at any given time. However, it took us a while to find out that MTBE was bad too. The oil companies never said anything. NTBE is not that far away in terms of chemical compounds. Why would it be any different in its effects on the environment?
Just my thoughts.
Additionally some thoughts. The dual octane rating for av fuels was the lean and rich octane rating. That’s what the engines could handle, and 100LL which isn’t really a low lead, according to some sections of the industry, wouldn’t work that well for all planes. However, we were forced to use it. I too, remember having to de lead trainer aircraft spark plugs every 50 hours, or the lead from the 100LL would foul the plugs to the point the engine would miss. Again, not a good fit.
John, One of the best documents regarding lower octane fuels (as low as 74), which probably had very little lead in it, is here. https://www.jstor.org/stable/44548241
It was written in 1946, and studied airline operations using water injection in order to use lower octane fuels to save money. The aircraft were not run rich. IIRC Water was turned on at a rate of 10% of the fuel by weight, and the engine was leaned for best power! This was take off power! In cruise at altitude, octane demand was lower anyway.
There are recent studies that show excess octane of 3 or so points reduces power as much as 5%.
Interesting point. The actual 100LL spec I think is 3.2 g/gallon. If the typical aircraft engine burns 18-20 g/h on takeoff, and the take off and initial climbout run time/distance to climb is about 5 minutes before first power reduction each airplane will burn around 2 gallons, and another 3 for start, warmup and taxi, plus what is dumped on the ground at preflight or about 10 g per departure in the vicinity of an airport. If it’s busy there’ll be about 10 departures/hour so about 100 g dispersed lead atmospheric lead. What happens afterwards? I don’t know, but the monitoring stations around airports have yet to show a significant increase in [Pb] in the region correlated to traffic. Automotive lead on the other hand was dispersed close to the ground on roadways, adjacent to crops and much more concentrated areas. It would be an interesting exercise to actually do some modeling of dispersal patterns of aircraft exhaust gases in each phase of flight. Wonderful opportunity for a dissertation thesis.
All of the concerns are valid, especially the alleged incompatibility between the the four (4) major unleaded fuel formulations. This was a non-issue in the transition to unleaded fuel for automobiles, why does the FAA and the EPA have to make things so much harder for pilots and their airplanes?
I repeat, the simplest solution is to sell both fuels side-by-side until leaded aviation fuel consumption drops to uneconomic levels, with a transition plan for the installed base of existing engines, combined with a requirement that all new airplanes be restricted to using the new unleaded fuels. If that had been the plan twenty (20) or thirty (30) years ago, we wouldn’t be having this discussion now, because the deed would have been done already! The fact that some of the research dates back to 1994 shows that this has been on the radar for over thirty (30) years now. So what the hell is taking so long?
Alternative power plants, like diesel engines, small turboprops and adopting automotive engine technology will help, as they offer an alternative to traditional spark-ignition gasoline engines for aviation, but engine replacements are expensive and time consuming. Offering financial help to aircraft owners, in the form of low-interest loans, grants or tax credits to expedite engine replacements, might be one way to speed up the process.
I’ve also seen studies of people living near airports, which show no increase of blood least levels over the general population.
Since the article is referring to an FAA document, it applies to the USA only. The Australian civil aviation authorities will have to make their own decisions.
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I fly an average of 200 hours a year, and haven’t burned a drop of avgas in 38 years, so don’t much care either way.
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